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abular fractures, with shorter surgery, instrumentation, intraoperative fluoroscopy times, and blood loss. Level of evidence Level III, Therapeutic study.Purpose The present study aimed to evaluate the scan technique of computed tomography (CT)-guided puncture procedures using partial exposure mode (PEM) on the radiation dose of the operator's hand and image quality. Methods Radiation dose was evaluated using three types of scanning methods one-shot scan (OS), OS with a bismuth shield added (OSBismuth), and a half-scan (i.e., PEM) capable of an adjustable exposure angle. Dose evaluation was performed using a torso phantom, while a circular phantom simulating the liver parenchyma and lesions was used for image quality evaluation. For each scanning method, four measurements were made to determine the radiation dose to the operator's hand and the dose distribution on the surface of the patient's torso; the output-dose profile was determined from five measurements. Image quality was evaluated in terms of contrast and contrast-to-noise ratio (CNR). Analysis of variance (ANOVA) or Friedman test were used for comparison between groups as appropriate. The post hoc tests were Tukey's honestly difference (HSD) test for parametric data or Wilcoxon signed rank test with Bonferroni correction for nonparametric data. Results The PEM yielded a radiation dose to the operator's hand that was 84% (0.35 vs. find more 2.33 mGy) lower than that of the OS. The dose to the patient's torso was reduced by 35% and 68% for the OSBismuth and PEM, respectively, relative to that of the OS. Compared with the CNR of the other two scanning methods (OS, 2.9±0.1; OSBismuth, 2.9±0.1), the PEM increased the standard deviation and decreased the CNR (2.1±0.04, Tukey's HSD, P less then 0.001 for all). Images acquired with PEM showed visibility equivalent to that of other scanning methods when window conditions were adjusted. Conclusion This study demonstrated that CT-guided puncture procedure using PEM effectively reduces the operator's exposure to radiation while minimizing image quality deterioration.Purpose We aimed to explore the influence of tube voltage, current and iterative reconstruction (IR) in computed tomography perfusion imaging (CTPI) and to compare CTPI parameters with microvessel density (MVD). Methods Hepatic CTPI with three CTPI protocols (protocol A, tube voltage/current 80 kV/40 mAs; protocol B, tube voltage/current 80 kV/80 mAs; protocol C tube voltage/current 100 kV/80 mAs) were performed in 25 rabbit liver VX2 tumor models, and filtered back projection (FBP) and IR were used for reconstruction of raw data. Hepatic arterial perfusion (HAP), hepatic portal perfusion (HPP), total perfusion (TP), hepatic arterial perfusion index (HPI), blood flow (BF) and blood volume (BV) of VX2 tumor and normal hepatic parenchyma were measured. Image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantified and radiation dose was recorded. MVD was counted using CD34 stain and compared with CTPI parameters. Results The highest radiation dose was found in protocol C, followed by protocols B and A. IR lowered image noise and improved SNR and CNR in all three protocols. There was no statistical difference between HAP, HPP, TP, HPI, BF and BV of VX2 tumor and normal hepatic parenchyma among the three protocols (P > 0.05) with FBP or IR reconstruction, and no statistical difference between IR and FBP reconstruction (P > 0.05) in either protocol. MVD had a positive linear correlation with HAP, TP, BF, with best correlation observed with HAP; MVD of VX2 tumor showed no or poor correlation with HPI and BV. Conclusion CTPI parameters are not affected by tube voltage, current or reconstruction algorithm; HAP can best reflect MVD, but no correlation exists between BV and MVD.Purpose Diagnosis of comorbid psychiatric conditions are a significant determinant for the prognosis of neurodegenerative diseases. Apathy, which is a behavioral executive dysfunction, frequently accompanies Alzheimer's disease (AD) and leads to higher daily functional loss. We assume that frontal lobe hypofunction in apathetic AD patients are more apparent than the AD patients without apathy. This study aims to address the neuroanatomical correlates of apathy in the early stage of AD using task-free functional magnetic resonance imaging (MRI). Methods Patients (n=20) were recruited from the Neurology and Psychiatry Departments of İstanbul University, İstanbul School of Medicine whose first referrals were 6- to 12-month history of progressive cognitive decline. Patients with clinical dementia rating 0.5 and 1 were included in the study. The patient group was divided into two subgroups as apathetic and non-apathetic AD according to their psychiatric examination and assessment scores. A healthy control group was also included (n=10). All subjects underwent structural and functional MRI. The resting-state condition was recorded eyes open for 5 minutes. Results The difference between the three groups came up in the pregenual anterior cingulate cortex (pgACC) at the trend level (P = 0.056). Apathetic AD group showed the most constricted activation area at pgACC. Conclusion The region in and around anterior default mode network (pgACC) seems to mediate motivation to initiate behavior, and this function appears to weaken as the apathy becomes more severe in AD.Purpose We aimed to assess the MRI findings and follow-up of multiple focal nodular hyperplasia (FNH)- like lesions in pediatric cancer patients diagnosed by imaging findings. Methods We retrospectively analyzed clinical data and MRI examinations of 16 pediatric patients, who had been scanned using gadoxetate disodium (n=13) and gadobenate dimeglumine (n=3). Hepatic nodules were reviewed according to their number, size, contour, T1- and T2-weighted signal intensities, arterial, portal, delayed and hepatobiliary phase enhancement patterns. Follow-up images were evaluated for nodule size, number, and appearance. Results All 16 patients received chemotherapy in due course. Time interval between the initial diagnosis of cancer and detection of the hepatic nodule was 2-14 years. Three patients had a single lesion, 13 patients had multiple nodules. The median size of the largest nodules was 19.5 mm (range, 8-41 mm). Among 16 patients that received hepatocyte-specific agents, FNH-like nodules appeared hyperintense in 11 and isointense in 5 on the hepatobiliary phase.